5. In the boiler shop of an electric power plant, 62 t of hard coal with calorific value Q=28.9 MJ/kg were burned during 20 hours of operation. Determine the average electric power of the plant if only 18% of the heat from the coal combustion is converted into electrical ener- gy.

To determine the average electric power of the plant, we need to follow these steps:<br /><br />1. **Calculate the total energy released from burning the coal:**<br /> - The mass of coal burned is \( 62 \, \text{t} = 62,000 \, \text{kg} \).<br /> - The calorific value of the coal is \( Q = 28.9 \, \text{MJ/kg} \).<br /><br /> The total energy released from burning the coal is:<br /> \[<br /> E_{\text{total}} = 62,000 \, \text{kg} \times 28.9 \, \text{MJ/kg} = 1,785.8 \, \text{MJ}<br /> \]<br /><br />2. **Calculate the useful energy converted into electrical energy:**<br /> - Only \( 18\% \) of the heat from the coal combustion is converted into electrical energy.<br /><br /> The useful energy is:<br /> \[<br /> E_{\text{useful}} = 0.18 \times 1,785.8 \, \text{MJ} = 322.844 \, \text{MJ}<br /> \]<br /><br />3. **Convert the useful energy into electrical power:**<br /> - The plant operates for 20 hours.<br /><br /> The average electric power \( P \) is:<br /> \[<br /> P = \frac{E_{\text{useful}}}{\text{time}} = \frac{322.844 \, \text{MJ}}{20 \, \text{hours}} = 16.1422 \, \text{MW}<br /> \]<br /><br />Therefore, the average electric power of the plant is \( 16.1422 \, \text{MW} \).